[MC1600]

Maybe this is confirmation bias because it's what I just did, but I would bite the bullet and buy new window assemblies while they're available and very reasonably priced when bought direct from GGS.  The new design is significantly better in my opinion.

You can replace the interior 'half' of the window assembly without removing the outside frame if you want.  It would give you an opportunity to check the condition of the coring and update to the new design without a huge time commitment. Just food for thought.

I got screens and gaskets.  What else would I need to replace?  My rings/glass are in excellent shape.  Is there something else in there I'm missing?